JP4907075B2 - Surface protective film for optical film - Google Patents

Description

The present invention relates to a surface protective film for optical films . The surface protective film for optical films of the present invention is used for protecting various optical film surfaces such as polarizing plates and retardation plates .

Specifically, the surface protective film for an optical film is a protection of an optical film such as a polarizing plate when the optical film is shipped, or a display device (liquid crystal module) of an image display device such as a liquid crystal display device. It is used for protecting optical films in various processes, such as protecting optical films during the manufacturing process.

  An optical film such as a polarizing plate is used for the liquid crystal display panel. A surface protective film is generally attached to the surface of the polarizing plate in order to protect the surface of the polarizing plate until the liquid crystal cell is assembled. Conventionally, the surface protective film has a biaxially stretched polyester film (polyethylene terephthalate film or the like) having a light-peelable pressure-sensitive adhesive layer that is releasably attached to the polarizing plate surface. As the pressure-sensitive adhesive layer, for example, many layers formed by applying an acrylic pressure-sensitive adhesive have been used.

  An optical film such as a polarizing plate is used as an optical film with an adhesive provided with an adhesive layer. When applying a surface protection film to such an optical film with an adhesive and punching it in a laminated state, a polarizing plate or the like is used on the back side of the surface protective film (the opposite side provided with the adhesive layer). Adhesives used are attached. Therefore, an antifouling treatment layer is provided on the back side of the surface protective film for facilitating removal of the adhesive and the like. Moreover, the surface protection film is generally provided with an antistatic layer for preventing static electricity on the back side of the surface protection film. The antistatic layer is usually provided between the film substrate and the antifouling layer (see, for example, Patent Document 1).

  However, in the surface protective film provided with the antifouling treatment layer and the antistatic layer on the back side, when wiping off the material attached to the antifouling treatment layer, the antistatic layer may be wiped off at the same time. There was a problem that the surface protective film had no antistatic effect.

In addition, with the recent increase in screen size of image display devices, when the surface protective film is peeled off, peeling workability is regarded as important, and it is desired that it can be easily peeled off with a light force.
JP 2001-209039 A

The present invention is a surface protective film for an optical film having an antifouling treatment layer on one side of a polyester film and an adhesive layer on the opposite side, and further having an antistatic layer, and is uniform as an antifouling treatment layer. It is an object of the present invention to provide a surface protective film for an optical film that has a layer and can maintain an antistatic effect even when a layer attached to the antifouling treatment layer is wiped off.

Another object of the present invention is to provide an optical film with a surface protective film to which the surface protective film for optical films is attached .

As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by an optical surface protective film shown below, and have solved the present invention.

That is, the present invention is a surface protective film for an optical film in which an antifouling treatment layer is provided on one side of a polyester film, and an adhesive layer is provided on the opposite side thereof,
The polyester film is not subjected to surface treatment,
An antistatic layer formed of a material containing an antistatic agent and a polyester-based binder is provided between the polyester film and the pressure-sensitive adhesive layer.
The present invention relates to a surface protective film for an optical film , wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer containing a hydroxyl group as a functional group and an isocyanate-based crosslinking agent.

  In order to solve the above-mentioned problems, the present inventors tried to provide an antistatic layer between the polyester film and the pressure-sensitive adhesive layer. However, the adhesion between the polyester film and the antistatic layer is not sufficient, and the antistatic effect cannot be maintained. On the other hand, in order to increase the adhesion between the polyester film and the antistatic layer, when the surface of the polyester film is subjected to a surface treatment such as a corona treatment, the polyester film itself is charged by the corona treatment or the like, and the antifouling treatment is performed. The layer is not evenly applied. Therefore, the effect of both the antifouling treatment layer and the antistatic layer cannot be maintained simply by providing the antistatic layer between the polyester film and the pressure-sensitive adhesive layer.

As a result of the above studies, the present inventors have developed the surface protective film for optical films . The surface protective film for optical films of the present invention uses a substrate that is not subjected to surface treatment such as corona treatment as a polyester film. Thereby, the antifouling treatment layer can be applied uniformly. On the other hand, by forming an antistatic layer with a material containing an antistatic agent and a polyester binder, it is possible to improve the adhesion between the antistatic layer and the polyester film even if the polyester film is not surface-treated. The antistatic effect can be maintained even when the material attached to the antifouling layer is wiped off. Furthermore, the adhesion between the antistatic layer and the pressure-sensitive adhesive layer is improved by forming the pressure-sensitive adhesive layer with an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer containing a hydroxyl group as a functional group and an isocyanate-based crosslinking agent. And the antistatic effect can be maintained. Such a pressure-sensitive adhesive layer can be designed to have good peelability.

The crosslinking agent of the prior SL adhesive layer, Ru using isocyanate crosslinking agent having an isocyanurate ring (triazine ring). An acrylic pressure-sensitive adhesive containing such a cross-linking agent is excellent in adhesiveness to the polarizing plate without the inclusion of bubbles, and can be easily peeled off with a light force when peeled off from the polarizing plate.

The surface protective film for optical films is suitably used for various optical films, but is particularly suitably used for protecting the surface of a polarizing plate.

Further, the present invention relates to an optical film, the affixed surface protective film for optical film, optical film with a surface protecting film, relates.

Hereinafter, the surface protective film for optical films of the present invention will be described with reference to the drawings. As shown in FIG. 1, the surface protective film for optical films of the present invention is provided with an antifouling treatment layer 1 on one side of a polyester film 2 that has not been surface-treated and an adhesive layer 4 on the opposite side. An antistatic layer 3 is provided between the polyester film 2 and the pressure-sensitive adhesive layer 4. In addition, the surface protection film for optical films of this invention can be used as a sheet-like material.

  The polyester film 2 is not subjected to surface treatment such as corona treatment. Examples of the polyester include polyethylene terephthalate and polyethylene naphthalate. Of these, polyethylene terephthalate is preferred. A stretched product such as a uniaxial or biaxial polyester film can also be used. The thickness of the polyester film is not particularly limited, but is preferably about 10 to 200 μm, particularly preferably 20 to 50 μm.

  For the formation of the antifouling treatment layer 1, various antifouling treatment agents such as a long-chain alkyl type and a silicone type can be appropriately used. Long-chain alkyl antifouling treatment agents include long-chain alkyl acrylate copolymers, long-chain alkyl vinyl ester copolymers, long-chain alkyl vinyl ether copolymers, long-chain alkyl acrylamide copolymers, maleic acid It is preferable to use a long-chain alkyl derivative copolymer, a long-chain alkyl esterified product of a hydroxyl group-containing polymer, a long-chain alkyl carbamate of a hydroxyl group-containing polymer, and the like. preferable. As the silicone-based antifouling treatment agent, either a condensation type silicone type or an addition type silicone type can be used.

  The antifouling treatment agent is diluted with a solvent such as toluene, ethyl acetate, or methyl ethyl ketone, and then applied to the polyester film 2 and dried to form the antifouling treatment layer 1. The thickness (dry film thickness) of the antifouling treatment layer 1 is not particularly limited, but is preferably about 10 to 1000 nm, particularly preferably 10 to 500 nm.

  The antistatic layer 3 is uniformly formed of, for example, an antistatic material containing an antistatic agent and a polyester binder. By using a polyester-based binder, the obtained antistatic layer 3 can improve adhesion even to a polyester film 2 that has not been subjected to a surface treatment such as a corona treatment.

  As the antistatic agent, various materials known as antistatic agents for polymer materials can be used. For example, cationic (for example, quaternary ammonium salt type, phosphonium salt type, sulfonium salt type, etc.), anionic type (for example, carboxylic acid type, sulfonate type, sulfate type, phosphate type, phosphite type, etc.), amphoteric ion type (For example, sulfobetaine type, alkylbetaine type, alkylimidazolium betaine type, etc.) or nonionic type (for example, polyhydric alcohol derivative, β-cyclodextrin inclusion compound, sorbitan fatty acid monoester / diester, polyalkylene oxide derivative, amine) Various surfactants such as oxides; cationic (eg, quaternary ammonium salts), zwitterionic (eg, betaine compounds), anionic (eg, sulfonates) or nonionic (eg, glycerin) Homopolymer of a monomer having an ion conductive group or a copolymer of the monomer and another monomer, a polymer having a site derived from an acrylate or methacrylate having a quaternary ammonium base, etc. A polymer having an ionic conductivity of: a permanent antistatic agent in which a hydrophilic polymer such as a polyethylene methacrylate copolymer is alloyed with an acrylic resin; acetylene black, ketjen black, natural graphite, artificial graphite, titanium And conductive fillers such as black, zinc oxide, tin oxide, tin-coated titanium oxide, nickel flakes, phosphorus-doped tin oxide, and antimony-doped tin oxide. Among these antistatic agents, a conductive filler of a metal compound such as tin oxide and a (meth) acrylic polymer containing a quaternary ammonium salt are preferably used from the viewpoint of antistatic performance. These components may be used alone or in combination of two or more.

  The polyester binder is not particularly limited, and a polyester binder obtained by dehydrating and condensing various polybasic acid components and polyol components by a known means can be used.

  Examples of the polybasic acid component include aromatic dibasic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and 5-sulfo (salt) isophthalic acid; succinic acid, glutaric acid, adipic acid, azelaic acid, Aliphatic dibasic acids such as sebacic acid, decanedicarboxylic acid, dodecanedioic acid, aicosane diacid, octadecanedicarboxylic acid; hexahydrophthalic acid, methylhexahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexane Alicyclic dibasic acid such as dicarboxylic acid; fumaric acid, dimer acid, α-, ω-1,2-polybutadienedicarboxylic acid, 7,12-dimethyl-7,11-octadecadien-1,18-dicarboxylic acid A dibasic acid having an unsaturated double bond such as hydride thereof, or 8,9-diphenylhexadecane Polybasic acids other than the above such as trimellitic acid. Examples of the polybasic acid component include acid anhydrides of the polybasic acid component and reactive derivatives such as dimethyl terephthalate. These components may be used alone or in combination of two or more.

  Examples of the polyol component include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, Examples thereof include polypropylene glycol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, α-, ω-1,2-polybutadiene glycol, bisphenol A, bisphenol F, and hydrides thereof.

  The polyester resin may contain a lactone such as caprolactone and a hydroxycarboxylic acid such as 4-hydroxybenzoic acid in part or all. The weight average molecular weight of the polyester resin is not particularly limited, but is preferably 1000 to 10,000.

  The blending amount of the antistatic agent with respect to the polyester binder is usually 50 to 400 parts by weight, preferably 100 to 300 parts by weight with respect to 100 parts by weight of the polyester binder.

  The antistatic layer 3 is formed by diluting an antistatic material containing an antistatic agent and a polyester binder with a solvent such as water or alcohol, and then applying and drying the polyester film 2 to form the antistatic layer 3. To do. The thickness (dry film thickness) of the antistatic layer 3 is not particularly limited, but is preferably about 50 to 500 nm, particularly preferably 80 to 300 nm.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 4, an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer containing a hydroxyl group as a functional group and an isocyanate-based cross-linking agent is used from the balance of transparency, cohesiveness, and peeling properties. It is done.

  The (meth) acrylic polymer in the present invention contains an alkyl (meth) acrylate and a hydroxyl group-containing monomer as monomer units. The technique for introducing a hydroxyl group is not particularly limited, but for example, a technique for copolymerizing a hydroxyl group-containing monomer can be easily performed.

  The (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or methacrylic polymer, (meth) acrylate refers to acrylate and / or methacrylate, and (meth) acrylate alkyl refers to acrylic acid. Alkyl and / or alkyl methacrylate.

  Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. Can be given. These compounds may be used alone or in combination of two or more.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, N-hydroxy (meth) acrylamide, Examples include vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. These monomers may be used alone or in combination of two or more.

  The hydroxyl group-containing monomer may be used alone or in combination of two or more, but the total content is 1 to 100 parts by weight of the (meth) acrylic polymer. The amount is preferably 10 parts by weight, and more preferably 2 to 6 parts by weight. By copolymerizing the hydroxyl group-containing monomer, a reactive site due to crosslinking or the like is given.

  The (meth) acrylic polymer used in the present invention preferably has a weight average molecular weight of about 300,000 to 2.5 million. When the weight average molecular weight is smaller than 300,000, the adhesive force tends to be generated due to the reduced cohesive force of the pressure-sensitive adhesive composition. A weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

  In addition, the glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower (usually −100 ° C. or higher), preferably −10 ° C. or lower for the reason that it is easy to balance the adhesive performance. When the glass transition temperature is higher than 0 ° C., the polymer is difficult to flow and the wetting to the polarizing plate is insufficient, and there is a tendency to cause blisters generated between the polarizing plate and the pressure-sensitive adhesive composition layer of the pressure-sensitive adhesive sheet. is there. In addition, the glass transition temperature (Tg) of a (meth) acrylic-type polymer can be adjusted in the said range by changing the monomer component and composition ratio to be used suitably.

  Moreover, as other polymerizable monomers other than the above-mentioned monomers, it is possible to use a polymerizable monomer for adjusting the glass transition point and peelability of the (meth) acrylic polymer as long as the effects of the present invention are not impaired. it can.

  Other polymerizable monomers used in (meth) acrylic polymers include, for example, cohesion and heat resistance of sulfonic acid group-containing monomers, phosphate group-containing monomers, cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers, etc. It has a functional group that acts as a crosslinking point and improves adhesion, such as an acid-improving component, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, N-acryloylmorpholine, and a vinyl ether monomer. Components can be used as appropriate. These monomer compounds may be used alone or in admixture of two or more.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth And acryloyloxynaphthalene sulfonic acid.

  Examples of the phosphoric acid group-containing monomer include 2-hydroxyethylacryloyl phosphate.

  Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

  Examples of the vinyl ester monomer include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

  Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, and the like.

  Examples of the acid anhydride group-containing monomer include maleic anhydride and itaconic anhydride.

  Examples of the amide group-containing monomer include acrylamide and diethyl acrylamide.

  Examples of the amino group-containing monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N- (meth) acryloylmorpholine, and alkylaminoalkyl (meth) acrylate. Examples include esters.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl ether.

  Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

  In the present invention, other polymerizable monomers may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferably 0 to 300 parts by weight, and more preferably 0 to 150 parts by weight.

  In addition, the polymerization method in particular of (meth) acrylic-type polymer is not restrict | limited, Well-known polymerization methods, such as solution polymerization, emulsion polymerization, suspension polymerization, and UV polymerization, are employable. Further, the obtained copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

  The pressure-sensitive adhesive composition of the present invention is based on the (meth) acrylic polymer as described above.

  In the present invention, an isocyanate-based crosslinking agent is used as the crosslinking agent. The isocyanate-based crosslinking agent is used for imparting adhesion and cohesion with the antistatic layer 3.

  As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound is used, and various compounds having two or more isocyanate groups in the molecule are included.

Examples of the isocyanate compound, b are particularly preferred those having isocyanurate ring, for example, polyisocyanates having long chain alkylene diol-modified isocyanurate ring (produced by Dainippon Ink and Chemicals, Inc., Burnock DN-995), hexamethylene diisocyanate isocyanurate Examples include nurate bodies (trade name Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.). These compounds may be used alone or in combination.

  The content of the crosslinking agent used in the present invention may be blended to such an extent that it does not affect the physical properties of the adhesive, but is usually contained in an amount of 0.2 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer, It is preferable that 0.5-8 weight part is contained, and it is more preferable that 1-6 weight part is contained.

  Note that acrylic adhesives include powders such as cross-linking agents (polyamine compounds, melamine resins, aziridine derivatives, urea resins), tackifiers, plasticizers, silane coupling agents, colorants, pigments other than those exemplified above. , Dyes, surfactants, surface lubricants, leveling agents, softeners, antioxidants, antistatic agents, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders Particles, foils, etc. can be used as appropriate. These components may be used alone or in combination of two or more.

  The method for forming the pressure-sensitive adhesive layer 4 is not particularly limited. For example, a method in which a pressure-sensitive adhesive solution is applied to a release liner such as a polyester film treated with silicone, dried, and then transferred to the antistatic layer 3 formed on the polyester film 2. (Transfer method), a method of directly applying an adhesive solution to the antistatic layer 3 formed on the polyester film 2 and drying (direct copying method), a method by coextrusion, and the like. Of these methods, the direct copy method is particularly preferable in order to further improve the adhesion to the antistatic layer 3.

  Moreover, in the formation method of the adhesive layer of this invention, you may use the well-known method used for manufacture of surface protection films. Specific examples include methods such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, and air knife coating.

Although the thickness (dry film thickness) of the said adhesive layer 4 is not restrict | limited in particular, Usually, about 5-60 micrometers, Preferably it is 5-40 micrometers. In addition, the adhesive layer 3 of the surface protective film for optical films of the present invention can be protected by temporarily attaching a separator or the like until practical use, if necessary.

  Examples of the constituent material of the separator (release sheet) include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foamed sheets, metal foils, and the like. An appropriate thin leaf body such as a laminate may be mentioned, and a plastic film is preferably used from the viewpoint of excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer. Examples thereof include a coalesced film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator (release sheet) is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator (release sheet), if necessary, release and antifouling treatment with silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., coating type, kneading An antistatic treatment such as a mold or a vapor deposition mold can also be performed. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the separator (release sheet).

Optical film with a surface protecting film of the present invention is formed by attaching the above surface protective film for an optical film to one or both sides of the optical film.

  As an optical film, what is used for formation of image display apparatuses, such as a liquid crystal display device, is used, and the kind in particular is not restrict | limited. For example, the optical film includes a polarizing plate. As the polarizing plate, one having a transparent protective film on one side or both sides of a polarizer is generally used.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and two colors such as iodine and dichroic dyes. Examples thereof include polyene-based oriented films such as those obtained by adsorbing volatile substances and uniaxially stretched, polyvinyl alcohol dehydrated products, and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride and the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

  As a material for forming the transparent protective film provided on one side or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer (AS resin) And styrene-based polymers such as, and polycarbonate-based polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.

  Although the thickness of a protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

  Moreover, it is preferable that a protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation value in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. In addition, when providing a protective film in the both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used. The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  Hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. with an appropriate ultraviolet curable resin such as acrylic or silicone It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

  Anti-glare treatment is applied for the purpose of preventing the external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by sandblasting or embossing. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles and organic fine particles composed of a crosslinked or uncrosslinked polymer are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  Examples of the optical member of the present invention include a liquid crystal display device such as a reflection plate, a semi-transmission plate, a phase difference plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, and a brightness enhancement film. What becomes an optical layer which may be used for formation is mention | raise | lifted. These can be used alone as the optical member of the present invention, and can be laminated on the polarizing plate for practical use and used in one or more layers.

  In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on a plate, or a polarizing plate in which a brightness enhancement film is further laminated on a polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Thus, there is an advantage that it is easy to reduce the thickness of the liquid crystal display device. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer, if necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. Moreover, the transparent protective film contains fine particles so as to have a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. The transparent protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it, and light and dark unevenness can be further suppressed. The reflective layer with a fine concavo-convex structure that reflects the surface fine concavo-convex structure of the transparent protective film is formed by transparent metal by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the protective layer.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate, etc. prevents the decrease in reflectance due to oxidation, and thus the long-term sustainability of the initial reflectance. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The transflective polarizing plate can be obtained by using a transflective reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate can save the energy of using a light source such as a backlight in a bright atmosphere, and is useful for forming a liquid crystal display device that can be used with a built-in light source in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black-and-white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which the image is displayed in color, and also has an antireflection function.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, norbornene resin, or binary, ternary various copolymers, graft copolymers Examples thereof include polymers and blends. These polymer materials become oriented products (stretched films) by stretching or the like.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include nematic alignment polyester liquid crystalline polymer, discotic polymer, cholesteric polymer, and the like having a structure in which a mesogenic group is bonded to a spacer portion that imparts flexibility. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers can be obtained by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as one obtained by rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate or one obtained by obliquely depositing silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, compensation for viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflection type) polarizing plate and a retardation plate. An optical member such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a viewing angle compensation phase difference plate include a phase difference plate, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, or a film obtained by obliquely aligning a liquid crystal polymer. can give. The raw material polymer of the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloring due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good viewing. An appropriate one for the purpose can be used.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to be incident to obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without being transmitted. The The light reflected from the surface of the brightness enhancement film is further inverted through a reflective layer provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display by supplying polarized light that is difficult to absorb into the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although it depends on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display is reduced accordingly, resulting in a dark image. In the brightness enhancement film, light having a polarization direction that is absorbed by the polarizer is reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflection layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed to the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., at the same time, the unevenness of the brightness of the display screen is reduced, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric or a multilayer laminate of thin film having different refractive index anisotropy. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that emits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer that has a reflection wavelength different from each other and has an arrangement structure in which two layers or three or more layers are overlapped to obtain a layer that reflects circularly polarized light in a wide wavelength range such as a visible light region. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  The optical member in which the optical layer is laminated on the polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. It is excellent in stability and assembly work, and has the advantage of improving the manufacturing process of a liquid crystal display device and the like. For the lamination, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  In addition, each layer such as an optical member or an adhesive layer of the pressure-sensitive adhesive optical member of the present invention includes, for example, ultraviolet rays such as salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like. What gave the ultraviolet absorptivity by systems, such as a system processed with an absorber, may be used.

  The pressure-sensitive adhesive optical member of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an adhesive optical member, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the optical member by invention, It can apply to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an adhesive optical member is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical member by this invention can be installed in the one side or both sides of a liquid crystal cell. When optical members are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative, or a stack of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described, but the present invention is not limited to these. In addition, the evaluation item in an Example etc. measured as follows. In the examples and the like, all parts and% are based on weight unless otherwise specified.

<Measurement of weight average molecular weight of (meth) acrylic polymer>
A sample (polymer) was spread thinly on a separator, air-dried, adjusted to a 1.0 (g / l) THF solution, and allowed to stand overnight.

  This solution was filtered through a membrane filter (0.45 μm), and the obtained filtrate was subjected to GPC (gel permeation chromatography) measurement (polymer weight average molecular weight).

Device: HLC-8120GPC, manufactured by Tosoh Corporation
column:
Sample column;
Made by Tosoh Corporation, TSK gel GMH-H (S) (2)
Column size: 7.8mmφ × 30cm each
Flow rate: 0.5ml / min
Injection volume: 100 μl
Column temperature: 40 ° C
Eluent: THF
Detector: differential refraction (RI) meter The weight average molecular weight was calculated in terms of polystyrene.

<Uniformity of antifouling treatment layer>
With the antifouling treatment layer of the surface protection film facing up, check whether the antifouling treatment layer was uniformly applied while holding the fluorescent light in the dark room, and visually evaluated the uniformity of the antifouling treatment layer . The evaluation criteria are as follows.

When evenly applied: ○
If uneven coating occurs: ×

<Adhesion>
The surface protective film was cut into a size of 10 cm in length and 5 cm in width. Next, the adhesive layer and the antistatic layer were scratched with a cutter so as not to scratch the base material in the vertical direction at the center in the longitudinal direction. The cellophane tape was affixed with a hand roller so as to straddle the scratch, and then removed and then affixed and removed again 20 times. The evaluation criteria are as follows.

When the adhesive layer or antistatic layer does not peel: ○
When peeled off with adhesive layer or antistatic layer: ×
When cellophane tape is applied to the adhesive layer and peeled off:-

<Adhesiveness>
A surface protective film is adhered to the surface of a polarizing plate (manufactured by Nitto Denko Corporation, AGSI) at room temperature with a laminator (bonding pressure: 0.3 MPa, speed: 1.0 m / min) to adhere the surface protective film. The aspect between the agent layer and the polarizing plate was visually evaluated.

Fine bubbles were generated: ×
Almost no fine bubbles were generated: ○

<Peelability>
A surface protective film was applied to the surface of a polarizing plate (manufactured by Nitto Denko Corporation, AGSI) at room temperature with a laminator (linear pressure: 78.5 N / cm, speed: 0.3 m / min), and at 50 ° C. for 3 days. After sticking and storing, it was left at room temperature for 2 hours. Thereafter, the 180 peel adhesive strength at 10 m / min and the actual peel feeling were examined. In addition, when the crosslinking reaction of the adhesive did not proceed and the glue remained, it was evaluated as “−”.

  From the viewpoint of surface protection, the adhesive strength is preferably 0.1 N / 25 mm or more, more preferably 0.2 N / 25 mm or more. On the other hand, from the viewpoint of peelability, the adhesive strength is preferably 1.0 N / 25 mm or less, more preferably 0.7 N / 25 mm or less.

[Example 1]
(Base material)
An untreated polyethylene terephthalate film (Mitsubishi Chemical Polyester, Diafoil T100 # 38) having a thickness of 38 μm was used.

(Anti-fouling treatment layer)
On one side of the untreated polyethylene terephthalate film, a 0.3% toluene solution of a long-chain alkyl-based polymer (manufactured by Yushi Kogyo Co., Ltd., Pyroyl 1010) was applied so that the dry film thickness was 50 nm, at 130 ° C. An antifouling treatment layer was formed by drying for 30 seconds.

(Antistatic layer)
On the opposite side of the untreated polyethylene terephthalate film on which the antifouling treatment layer is formed, a 5% mixed solution (water) of an antistatic layer forming material (Microsolver RW-922, manufactured by Solbex, Inc.) containing a polyester binder and tin oxide. / Methanol = 5/5) was applied so that the dry film thickness was 300 nm, and dried at 130 ° C. for 30 seconds to form an antistatic layer.

(Adhesive layer)
In ethyl acetate, 100 parts by weight of 2-ethylhexyl acrylate and 4 parts by weight of 2-hydroxyethyl acrylate are copolymerized so as to be 35% on a monomer basis to obtain a solution containing an acrylic polymer having a weight average molecular weight of 600,000. It was. Into this solution, 4 parts by weight of an isocyanate-based cross-linking agent having an isocyanurate ring (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) is blended with 100 parts by weight of an acrylic polymer (dry weight), and ethyl acetate is further added to form a solid. A pressure-sensitive adhesive solution with a partial concentration adjusted to 20% was prepared. The pressure-sensitive adhesive solution was applied on the antistatic layer so as to have a dry film thickness of 20 μm, and dried at 140 ° C. for 2 minutes to form a pressure-sensitive adhesive layer, thereby obtaining a surface protective film.

[Example 2]
In Example 1, the surface protection film was obtained according to Example 1 except having made the dry film thickness of the adhesive layer into 25 micrometers.

Example 3
In Example 1, a surface protective film was obtained according to Example 1 except that the antistatic layer was changed to 100 nm.

Example 4
In Example 1, the surface protection film was obtained according to Example 1 except having changed the compounding quantity of the crosslinking agent used for the adhesive solution into 3 weight part of isocyanate type crosslinking agents.

[Comparative Example 1]
In Example 1, the amount of the crosslinking agent used in the pressure-sensitive adhesive solution was changed to 3 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Co., Ltd., Tetrad C). Got.

[Comparative Example 2]
(Base material)
A 38 μm-thick one-side corona-treated polyethylene terephthalate film (Mitsubishi Chemical Polyester, Diafoil T100 C38) was used.

(Antistatic layer)
An anti-stain treatment layer is formed on the non-corona surface of the one-side corona-treated polyethylene terephthalate film, and an antistatic layer forming material containing a polyester-based binder and tin oxide on the other side (corona surface) (manufactured by Solvex, Microsolver) RW-922) 5% mixed solution (water / methanol = 5/5) was applied to a dry film thickness of 300 nm and dried at 130 ° C. for 30 seconds to form an antistatic layer.

(Adhesive layer)
In ethyl acetate, 100 parts by weight of 2-ethylhexyl acrylate and 3 parts by weight of acrylic acid were copolymerized so as to be 35% on a monomer basis to obtain a solution containing an acrylic polymer having a weight average molecular weight of 500,000. To this solution, 4 parts by weight of an epoxy crosslinking agent (Mitsubishi Gas Co., Ltd., Tetrad C) is blended with 100 parts by weight of an acrylic polymer (dry weight), and ethyl acetate is added to make the solid content concentration 20%. An adjusted pressure-sensitive adhesive solution was prepared. The pressure-sensitive adhesive solution was applied on the antistatic layer so as to have a dry film thickness of 20 μm, and dried at 140 ° C. for 2 minutes to form a pressure-sensitive adhesive layer, thereby obtaining a surface protective film.

[Comparative Example 3]
(Antistatic layer)
In Example 1, an antistatic layer-forming material (Microsolver LS-110, manufactured by Solbex Co., Ltd.) 5 containing an acrylic binder and tin oxide was formed on the opposite side of the untreated polyethylene terephthalate film where the antifouling layer was formed. % Mixed solution (water / methanol = 5/5) was applied so that the dry film thickness was 300 nm and dried at 130 ° C. for 30 seconds to form an antistatic layer.

(Adhesive layer)
In ethyl acetate, 100 parts by weight of 2-ethylhexyl acrylate and 3 parts by weight of acrylic acid were copolymerized so as to be 35% on a monomer basis to obtain a solution containing an acrylic polymer having a weight average molecular weight of 500,000. To this solution, 4 parts by weight of an epoxy crosslinking agent (Mitsubishi Gas Co., Ltd., Tetrad C) is blended with 100 parts by weight of an acrylic polymer (dry weight), and ethyl acetate is added to make the solid content concentration 20%. An adjusted pressure-sensitive adhesive solution was prepared. The pressure-sensitive adhesive solution was applied on the antistatic layer so as to have a dry film thickness of 20 μm, and dried at 140 ° C. for 2 minutes to form a pressure-sensitive adhesive layer, thereby obtaining a surface protective film.

[Comparative Example 4]
(Adhesive layer)
In Example 1, a solution containing an acrylic polymer having a weight average molecular weight of 500,000 by copolymerizing 100 parts by weight of 2-ethylhexyl acrylate and 3 parts by weight of acrylic acid so as to be 35% on a monomer basis in ethyl acetate Got. To this solution, 4 parts by weight of an epoxy crosslinking agent (Mitsubishi Gas Co., Ltd., Tetrad C) is blended with 100 parts by weight of an acrylic polymer (dry weight), and ethyl acetate is added to make the solid content concentration 20%. An adjusted pressure-sensitive adhesive solution was prepared. The pressure-sensitive adhesive solution was applied on the antistatic layer so as to have a dry film thickness of 30 μm, and dried at 140 ° C. for 2 minutes to form a pressure-sensitive adhesive layer to obtain a surface protective film.

  In accordance with the above method, the evaluation of the occurrence of uniformity, adhesion, bonding, and peelability of the antifouling treatment layer was performed. The obtained results are shown in Table 1.

上記表１の結果より、本発明によって作製された光学フィルム用表面保護フィルムを用いた場合（実施例１〜４）、いずれの実施例においても、防汚処理層の均一性、密着性、貼り合せ性、および剥離性のすべてをバランスよく並立するものであった。

From the results of Table 1 above, when the surface protective film for an optical film produced according to the present invention was used (Examples 1 to 4), the uniformity, adhesion, and adhesion of the antifouling treatment layer in any of the Examples. The matching property and the peeling property were all arranged in a balanced manner.

On the other hand, in any of Comparative Examples 1 to 4, it was difficult to arrange all of the uniformity, adhesion, bonding, and peelability of the antifouling treatment layer in a well-balanced manner. Therefore, it became clear that all the comparative examples were inferior to the surface protective film for optical films .

Therefore, the surface protective film for optical films of this invention has confirmed that it was a surface protective film for optical films which can maintain an antistatic effect, even when the thing adhering to the antifouling process layer was wiped off.

It is an example of sectional drawing of the surface protection film for optical films of this invention.

Explanation of symbols

1 Antifouling treatment layer 2 Polyester film not subjected to surface treatment 3 Antistatic layer 4 Adhesive layer

Claims (4)

Antifouling layer on one side of the polyester film, opposite to the pressure-sensitive adhesive layer is provided that, a surface protecting film for an optical film,
The polyester film is not subjected to surface treatment,
An antistatic layer formed of a material containing an antistatic agent and a polyester-based binder is provided between the polyester film and the pressure-sensitive adhesive layer.
The surface protective film for optical films , wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer containing a hydroxyl group as a functional group and an isocyanate-based crosslinking agent having an isocyanurate ring . The antistatic agent includes at least one selected from the group consisting of a surfactant, a polymer of a monomer having an ion conductive group, a polymer having an ionic conductivity, a permanent antistatic agent, and a conductive filler. The surface protective film for optical films of Claim 1 containing. The surface protective film for an optical film according to claim 1, which is used for surface protection of a polarizing plate. The optical film with a surface protection film with which the surface protection film for optical films in any one of Claims 1-2 is stuck to the optical film.

Images